1. Field of the Invention
The invention concerns a measuring circuit for a modular system of electrical modules connected in series and in particular for a system of modules each consisting of one or more elements for producing, storing or converting electrical energy. It is more particularly concerned with systems comprising multiple modules operating at a high voltage.
2. Description of the Prior Art
The operation of systems of electrical modules connected in series can be largely optimized, in particular when the number of modules is relatively large, if it is possible to monitor the operation of each module accurately and consequently to carry out measurements module by module.
U.S. Pat. No. 5,638,002 describes a measuring circuit for such systems of modules. It provides accurate measurements and reduces the number of electrical connections needed to transmit measurement signals. A first serial link connects measurement interfaces individually assigned to the modules and enables a common transducer to handle successively measurement signals obtained by means of current generators at the interfaces. A second serial link transmits individual selection pulses to the interfaces from a common logic unit.
In some cases it is beneficial to have a high voltage at the terminals of a system of modules, for example to drive the motor in an electric vehicle. This has repercussions in terms of the interfaces of the measurement circuit for a system of modules of this kind, in that the interface components may be required to withstand a high voltage, possibly as high as the voltage at the terminals of the system, and malfunctions that can occur during operation of the system of modules can lead to the occurrence of abnormal voltages and in particular reverse voltages at the input/output terminals of the interfaces.